[ Gustavo Pichorim Boiko ]
* Add the infrastructure to write tests for the handler, and write
tests for the most important bits of it.
* Make the dbus-based tests more robust. (LP: #1270778)
* Improve the support for handling multiple calls by: Using a
different approach to detect background calls in the QML plugin.
Make it possible to hangup the active call to answer an incoming
one. Show notifications when calls are put on hold, when they are
rejected and when they end. .